A Component Level Test Methodology to Validate Hydraulic Clutch Slave Cylinder

In this current fast-paced world, releasing a defect free product on time is of utmost importance in the automotive domain. The automobile powertrain is designed with a fine balance of weight and power. Clutch, an intermediate part between engine & transmission in manual transmission vehicle plays crucial role for vehicle smooth drive & functionality. Hydraulic clutch slave cylinder (CSC) which is a part of clutch release system was observed with one failure mode in one of the vehicles during internal road validation. It facilitates to actuate the clutch diaphragm in order to disengage the clutch when clutch pedal is pressed and to re-engage the clutch back when the clutch pedal is released. CSC failure directly disconnects the response of leg to clutch and thus driver may lose vehicle control and can possibly cause a severe vehicle crash. After investigation and dismantling the failed part, wear marks were observed on anti-rotation pin (which locks CSC hydraulic chamber against plastic body) and on elliptical O-ring, which locks oil flow to the plastic chamber. Unique in the industry, a component-level test setup was developed for validation and improved CSC design. Few samples were successfully tested for failure simulation and results were very encouraging. For strengthening of the CSC, design modification was done, and the new designed parts were tested on the same component-level test setup for validation. The sample passed the component-level test, and subsequently vehicle level test, and was approved for production. The component-level test methodology helped to test multiple design iterations and samples within a postulated time and cost. This methodology can be used as a part of front-loading support for all future projects.